Butterfly

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[Diagram]

The butterfly

The name for this three-stone enclosure, and the advice to avoid it, come from a Korean web site.

A duller name would be 374473 enclosure. This is one of a number of unusual three-stone enclosures that are being seen more frequently in pro games.

[Diagram]

3-3 invasion becomes ko

This sequence occurred in a game of Dosaku (in 1678) and also in a game Yu Bin-Seo Pong-su in 2000. White 11 at a, Black at b, White at c sets up a ko; if White wins the ko the damage to Black's position will be serious, so this may almost be a picnic ko from White's point of view.

[Diagram]

The butterfly

In practice, though, Black probably played at least one of the marked stones as a checking extension against a corresponding white stone. That makes the marked points interesting as possible invasions for White: if they connect out, a weak white group will gain in strength.


[Diagram]

Orthodox

Black 1 here is the normal idea. The invasion point at a is then just some bad aji, not something White can use successfully at once.

For a little general discussion, see unusual three-stone enclosures.

Charles Matthews


This is a copy of the living page "Butterfly" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.
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